SNPs Identification Of Growth-related Genes And Correlation Analysis On Genetic Effect In Tilapia Species

In recent years,with the rapid development and widespread application of DNA molecular marker technology,traditional breeding combined with molecular marker technology had been the effective means to cultivate new strains of fish.Besides,We can find new molecular markers or genes which are related to important economic traits by molecular assisted selection.Our study was conducted according to five important economic traits such as body weight,body length,body height,body width and head,we had screened the molecular markers related to the growth traits of tilapia,explored the mechanism and interaction between them.The results showed that there were significant differences in the growth rate of Nile tilapia among different families or different individuality from the same families,and there were some differences in morphology,which indicated that the genetic diversity was rich in the population,and the breeding space was relatively large.In order to ensure that the rapid growth and good traits of tilapia can be stably inherited,and cultivate new strains with faster growth rate,we studied the five genes of Mylospora,such as MyoDl,MyoD2,Myostatin,GH and IGF2 genes.The SNPs were obtained by PCR-SSCP and sequencing techniques.The association between SNPs genotype and tilapia growth traits was analyzed by least squares method,and we obtained the relationship between the SNPs and the growth of tilapia to lay the foundation for molecular assisted breeding research of Nile tilapia.The results of this study are as follows:1.A total of 8 SNP loci were detected in the MyoD1 gene of Nile tilapia,296A ?C,32T?C,617G?C,659A?G,770C?G,1176G?A,1195C?A,2367A?G(P>0.05),and five SNP loci were in Hardy-Weinberg equilibrium(P<0.01).Three SNP loci were in Hardy-Weinberg equilibrium state(P>0.05).2.Two SNPs were detected in the MyoD2 gene of Nile tilapia,which were 636'T ? C,1127C?T,1357A?T,respectively.The loci were found at the site of 1127C ?T in Hardy-Weinberg Unbalanced state(P<0.05).3.Three SNPs were detected in the Myostatin gene of Nile tilapia,and 617A?T,725C?T,2129A?C,respectively.The results showed that the locus 2129A?C was in Hardy-Weinberg Very unbalanced state(P<0.01).4.A SNP site of the GH gene of Nile tilapia was detected,that is,1146T?A,the site balance test showed that the site 2129A?C was in the Hardy-Weinberg unbalanced state(P<0.01).5.A total of 6 SNPs were detected in the IGF2 gene of Nile tilapia,which were 1017G?T,1018G?T,1075C?T,1467C?T,1472C?Q 4438C?T,respectively.It was found that three SNPs were in Hardy-Weinberg imbalance(P<0.05),and no SNP locus was in Hardy-Weinberg unbalanced state(P<0.01).There were allele loss danger.6.The SNP locus of MyoD1 gene of Nile tilapia showed that the 296A?C polymorphism locus was significantly correlated with the length and body length of female Nile tilapia(P<0.05)(P<0.05).The 323T?C polymorphism was significantly correlated with the weight of female Nile tilapia(P<0.05).7.SNP analysis of four genes of MyoD2,Myostatin,GH,IGF2 in Nile tilapia showed that the SNPs of four genes were related to the body weight,body length,head length,body width and body length of Nile tilapia There was no significant correlation between high growth traits(P>0.05).In this study,we provides a molecular genetic reference for those syudies,such as improved the Nile tilapia varieties by means of molecular markers,and shortened the breeding period to achieve maximum economic benefits,and achieve the excellent economic traits of tilapia,and the best combination and strengthening of our tilapia breeding technology system,and so on.